Re: Airtight Coil form

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Tesla729-at-cs-dot-com>

In a message dated 3/13/01 9:59:55 PM Pacific Standard Time, tesla-at-pupman-dot-com 
writes: 


>
> I haven't been able to find an answer to 
> the question of why does the coil form need to be airtight.  I thought it 
> might be due to internal arcing, but that didn't make sense since arcs can 
> still happen in a vacuum. I figured this would be the best place to get an 
> answer from, since a majority of you are what I would consider experts. 
> Thanks! 
>
>



Hi Mark, 

While I certainly wouldn't consider myself an "expert", I 
have personally never heard of a secondary coil form need- 
ing to be "airtight". If you choose to use cardboard as the 
former, then you'll need to make sure it's moisture-tight by 
applying several coats of polyurethane to it before winding 
the coil on it. Also, most coilers apply polyurethane or some 
epoxy coating on the finished secondary coil to insure good 
insulation and protection of the secondary coil, regardless of 
what the form material is. 

Many coilers also equally space 2 to 4 plastic disc along the 
inside of the secondary coil form to prevent internal tracking 
and flashover. 

Hope this helps, 
David Rieben